What were .plan files like? I've only ever heard of Carmack using them -- did other prominent devs also publish their .plans? I wonder if there'd be any interest in reviving this. I think it would be cool to have something like an RSS feed of the .plan files from various developers I respect/follow. These days you have to settle for reading their Twitter+GitHub issues.
(There were actually two such files; .project was used to give a high-level summary of what you were working on, while .plan was used to talk in detail about what you were currently doing at the moment.)